Shareholders' Equity - Option Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Plan Shares Available for Grant
Balance at the beginning of the period (in shares)	477,534	307,767
Shares reserved	0	200,000
Balance at the end of the period (in shares)	501,622	477,534
Stock Option Plan2013 [Member] | Board Of Directors [Member]
Plan Shares Available for Grant
Stock awards granted (in shares)	(54,036)	(37,233)
Employee Stock Option [Member]
Plan Shares Available for Grant
Stock options granted (in shares)	(20,000)	(200,000)
Plan Options Outstanding
Balance at the beginning of the period (in shares)	895,161	1,255,077
Stock options granted (in shares)	20,000	200,000
Stock options exercised (in shares)	(227,833)	(113,837)
Balance at the end of the period (in shares)	419,162	895,161
Weighted Average Exercise Price Per Share
Balance at the beginning of the period (in dollars per share)	$ 2.73	$ 2.86
Stock options granted (in dollars per share)	2.90	2.82
Stock options exercised (in dollars per share)	1.72	1.90
Balance at the end of the period (in dollars per share)	$ 3.18	$ 2.73
Aggregate Intrinsic Value, Stock options exercised (in dollars)	$ 143,531	$ 105,012
Employee Stock Option [Member] | Stock Option Plan2013 [Member]
Plan Shares Available for Grant
Cancelled or forfeited (in shares)	237,500	279,000
Plan Options Outstanding
Cancelled or forfeited (in shares)	(237,500)	(279,000)
Weighted Average Exercise Price Per Share
Cancelled (in dollars per share)	$ 2.86	$ 2.87
Employee Stock Option [Member] | Incentive Stock Option Plan2003 [Member]
Plan Options Outstanding
Cancelled or forfeited (in shares)	(30,666)	(167,079)
Weighted Average Exercise Price Per Share
Cancelled (in dollars per share)	$ 3.22	$ 4.13
Restricted Stock and Restricted Stock Units [Member]
Plan Shares Available for Grant
Restricted stock and restricted stock units granted (in shares)	(189,875)	(99,000)
Restricted Stock and Restricted Stock Units [Member] | Stock Option Plan2013 [Member]
Plan Shares Available for Grant
Restricted stock and restricted stock units granted (in shares)	(189,875)	(99,000)
Cancelled or forfeited (in shares)	50,499	27,000
Weighted Average Exercise Price Per Share
Cancelled, restricted stock units (in dollars per share)	$ 2.72	$ 2.89